Production of magnesium.



P. VON KfiG LGBN & G. 0. SBWARD.

' PRODUCTION OF MAGNESIUM.

APPLIOATION FILED JULY 8, 1907.

935,796, Patented Oct 5, 1909."

FIG.

FIG. 2.

outrun PATENT orrion CIRA'NZ VON xuemn'enn, or HoLcoMns ROCKVIRGINIA.Ann enonen'o. snwnnn; or

EAST ORANGE, NEW JERSEY, ASSIGNORS TO vmemre NEW YORK, n. Y., Aoonronarron or NEW roux.

ILABORATORY COMPANY, OF

. rizoimc'rron or MAGNESLUM.

Specification of Letters Patent. Patented Oct. 5, 1909.

Application filed July 8, 1907.. Serial Nb. 332,596.

To all'whom it may concern: .1

Be it known that we, FRANLyoN KilGEL- only, a ubject ofthe-*GermanEmperor, res ding Holcombs Rock, in the county of Bedford andState of Virginia, and GEORGE O. SEWAnD, a citizen ofthe United States,residing at East Orange, in the county of Essex and State of New Jersey,have jointly invented certain new and usefullmprovements in theProduction of Magnesium, of

' .which the following is a specification.

can be used tolower the specific gravity of to insure a good Theproduction of magnesium by the electrolysis of its molten chlorid isdrfiicult for the reason that the specific gravity of the electrolyte isvery nearly the same as that of the metal and there are no fluxes whichthe electrolyte sutficient-ly separation of the metal therefrom.

Moreover, it is exceediugly difficult to avoid the introduction ofimpurities such as iron when preparing the electrolyte, and

such impurities,-being.-less 'electro-positive than magnesium anddeposltxing together with magnesium,cause the formation of a I spongydeposit of metal at the cathode which prevents the merging of theglobules of ma nesium.

he present invention provides a method for the production of magnesiumwhich overcomes the above-mentioned difiiculties and which ischaracterized by being a pr'oc- I ess 1n two steps or operations.

The first step produces an alloy of magnesium with a lesselectro-positive metal-by clectrolyzing a molten magnesium electrolyteWith'a-n insoluble anode and a cathode of a molten me al, less 7electro-positive than magnesium. T esec such alloy,

ondstep produces 'pure magnesium by consecutivefdissolution anddeposition from the latter being used as the anode in -a suitableelectrolyte. In the first step the initial electrolyte, are separatedtogether with the magnesium and are absorbed by the molten alloy of thecathode. In the second step these impurities, beingles'selectro-positive than magnesium, are not dissolved there with 'butremain in the molten anodenpure magnesium being lthus produced. In thefirst'step an electrolyte of lows ecific gravity is used so 'thatanalloy very ich in mag nes1u1ir:can be. produced Without danger ofelectrolytic vessel. In the second step an I electrolyte is used ofsufiiciently high spegcific gravity to insure the rapid flotation i ofthe magnesium to the surface as soon as fdeposited and its collectionthere. As a 1 cathode in the first step, We select a metal j which (1)alloys easilywith magnesium and forms a sufficiently fusible alloytherewith; (2) is capable of dissolving the impurities of theelectrolyte which are less electro-positive than magnesium, and henceare deposited therewith; (3) is less electro-positive than magnesium sothat, in the second step of the process, it remains unchan ed while themagnesium dissolves in' the electrolyte. Aluminum combines these threeproperties and is a suitable metal for the cathode alloy. In practicingour invention We proceed preferably as follows :-We subject a moltenelectrolyte of the approximate composition MgClH-KCI to the action of acontinuous electric current in a suitable vessel, using carbon anodesand a cathode of molten aluminum. The magnesium produced at the cathodealloys with the aluminum. As the electrolysis proceeds the alloy becomesricher in magnesium; when it contains from '50 to 60 per cent. ofmagnesium it is removed either in whole or in part and is used as theanode in the second step of the process,

The electrolyte in the second step may-be that a certain proportion of aheavy salt of a more electro-positive metal than magnesium- (e. g.lmrilnn-chlorid) is added to increase the specific gravity andfacilitates the flotation of the magnesium. As magnesium is dissolvedfrom the anode to the same extent as it is deposited. at the cathode,the electrolyte in the second step ofjthe process remains substantiallyunchanged. A Magne- -sium,being the most electro-positive constituent ofthe molten anodedncthe second step of the process, is alone dissolvedand redeposited, care being taken to avoid exhaustng the anode content.

is a Vertical-section of a suitable electrosuitable for the second step.

too much of its magnesium lytic cell for use; in the first step of theprocess, and Fig. 2 as similar section of a cell Referiing to Fig. 1,theelectrolytic cellsimilar to that in the first step excepting In theaccompanying drawings, Figure 1 or vessel Ais shown as constructed witha. receptacle C, which may be of cast metal, having a carbon lining D inits lower part and a water-jacket E surrounding 1ts upper portion,whereby the electrolyte 1s chilled or incrusted to form a protectivecoatmg'F. The vessel is covered by a top or lid G, which may be ofgraphite, and which is separate'd from the metal vessel below by aninsulating layer H. Through the graphite top project one or more anodesJ J which may be of graphite. These are connected to the positlveterminal of the dynamo or other generator K, its'negative terminal beingconnected tb' the vessel C or carbon l1 ning D. A tap-hole L is providedthrough which to draw o'fi the aluminum. An opening Q may-be for theescape 0 chlorin.

Referring to Fig.2 the electrolytic cell or vessel B in which the secondstep of the process is performed, may be in general of somewhat similarconstruction to the vessel A. Its body or receptacle C may be aduplicate of the vessel C, with a carbon lining D and a water jacket E,forming a chilled layer of salt F and having a tap-hole L.

The cover G is here shown of cast metal separated from the vessel C byinsulation H. The cover has a flange I projecting down beneath thesurface of the electrolyte, so that it may serve initially as thecathode. It may also have a suitable lid M. The positive terminal of thegenerator K is connected to the vessel G or lining D, while its negativeterminal is connected to the cover G. j

In operation, the alloy of magnesium and aluminum which is, obtained invessel A is used as the anode in vessel B. After the second step hasbeen in progress for a short time the separated magnesium covers thesurface of the electrolyte and acts as the true cathode. I

The operation in vessel A is made continuous by tapping off a part ofthe electr'olyte from time to time and replacing it by exhausted alloyfrom the anode of vessel B.

The operation in vessel B is made continuous by removing alarge part ofthe magnesium from time totime, and bytapping most of the nearlyexhausted alloy of 1 the anode from time to time and replacing by richalloy from vessel A. r

Though we have described the use of a chlorid electrolyte in both stepsof our invention, we do not confine ourselves to such use, but may useany suitable electrolyte for 1 either stepof the process. a

We are aware that impure aluminum has been purified by using it. as theanodeand dissolving it by electrolyzingwith a solvent electrolyte,redepositing the resulting pure aluminum at the cathode. But we are notaware that this process-has been applied rovided through the lid Gduction of magnesium by the electrolysis of its chlorid as hereinbeforestated, are dift'erent from those existing with aluminum. .4 .By ourinvention we make as the first step of the process asuitable alloy ofmagnesium, solely in order that we-may use this alloy as the anode inthe final step of the process, from which to dissolve out therefrom thepure magnesium and collect it at the. to of the electrolyte. We thusavoid the di culty herein stated that in the direct production ofmagnesium from its molten chlorid the specific gravity of theelectrolyte is so nearly that of themetal as to impede the separation ofthe metal therefrom.

We claim as our invention 1. The process of obtaining magnesium whichconsists in producing an alloy of magnesium with a less electro-positivemetal by electrolyzing a suitable electrolyte with a cathode of saidmetal; and subsequently dissolving the magnesium out of said alloy byusing the latter as an anode with a suitable molten electrolyte and'depositing the magnesium at the cathode.

2. The process of obtaining magnesium which consists in electrolyzing amagnesium salt with a cathode of a metal less electropositive thanmagnesium and 'whichforms therewith an alloy of lower melting point; andsubsequently dissolving athe magnesium out of said alloy by using thelatter asan anode with a suitablemol'ten electrolyte and depositing themagnesium at the cathode.

3. The. process of obtaining magnesium which consists in electrolyzingfused magnesiumchlorid with a cathode of a metal less electro-positivethan ma nesium'to form an alloy therewith; and su sequently dissolvingthe magnesium out of said alloy by using the latter as an anode with asuitable molten electrolyte and depositing the magnesium at the cathode.

4. The process of obtaining magnesium.

which consists in electrolyzing a magnesium J1 salt with a cathode ofmolten alumlnum to produce a magnesium-aluminum alloyg'and,

subsequently dissolving the magnesium-out of said alloy by using thelatter'as ananode' witl 1 a suitable molten electrolyte and. depositingthe magnesium at the cathode;

5. The process-of. obtaining mag esimn.

aluminum alloy thereby addin ma'gnesiumto such alloy; and subsequent ydissolving the magnesium out of said alloy and using the latter as ananode witha suitablemolten electrolyte and depositing-the magnesiinnatthe .cathode.

which consists in electrolyzlngmagnesium 6. The process of obtainingmagnesium gravity,,whereby the magnesium separated. at the cathode iscaused to float upon the l0 chlorid with a cathode of molten aluminum toform a niagnesiinn-aluminum alloy; and subsequently dissolving themagnesium out of said alloy by using the latter as an anode with anelectrolyte of magnesium chlorid. to which is added a heavy salt of amore electro-positive metal to increase its specific electrolyte.

7. In the process of obtaining magnesium by first electrically producingan alloy thereof with another metal, the step of recovering themagnesium from said alloy which consists in electrolyzing'an electrolyteof a magnesium salt to which a heavy salt of a more electro-positivemetal has been added to increase its specific gravity, using said alloyas the anode whereby magnesium is dissolved out therefrom and depositedat the 20

